WASHINGTON (Reuters) - U.S. regulators on Friday said
Pfizer Inc's anti-smoking drug Chantix appears increasingly
likely to be linked to serious psychiatric behavior, and called
for stronger label warnings.

The Food and Drug Administration said after an analysis of
reports of suicidal thoughts and behavior potentially linked to
the medication, it was calling for Pfizer to strengthen the
label warnings on the drug.

FDA said the drug is effective but that patients should
talk to their doctors about this new safety information.

The drug has been prescribed to about 4 million people in
the United States since approval in 2006, according to Pfizer.